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Message-Id: <200701262034.03554.pisa@cmp.felk.cvut.cz>
Date: Fri, 26 Jan 2007 20:34:02 +0100
From: Pavel Pisa <pisa@....felk.cvut.cz>
To: tglx@...utronix.de
Cc: Ingo Molnar <mingo@...e.hu>, linux-kernel@...r.kernel.org,
Sascha Hauer <s.hauer@...gutronix.de>
Subject: Re: [PATCH updated] arm: i.MX/MX1 clock event source
On Wednesday 24 January 2007 12:37, Thomas Gleixner wrote:
> On Wed, 2007-01-24 at 03:00 +0100, Pavel Pisa wrote:
> > stays NULL after clock event registration. Interrupts
> > runs, but my code doesnot call any function. The notification
> > chain and clock events list seems to be filled correctly.
> > I have added
> >
> > clockevent_imx.cpumask = cpumask_of_cpu(0);
>
> Correct. I probably should disable the check for UP.
I have made mistake last time on 2.6.20-rc5-rt8.
I have returned to testing today with 2.6.20-rc6-rt2.
I have added checking outputs to the tickregistration
routines, but all works correctly after right cpumask correction.
I have rechecked even without additional printks
and I have observed no problems. The clock events enabled kernels
requires next minor changes to compile on ARM still
================================================================================
================================================================================
arch/arm/kernel/process.c | 5 +++--
kernel/time/tick-sched.c | 1 +
2 files changed, 4 insertions(+), 2 deletions(-)
Index: linux-2.6.20-rc6/kernel/time/tick-sched.c
===================================================================
--- linux-2.6.20-rc6.orig/kernel/time/tick-sched.c
+++ linux-2.6.20-rc6/kernel/time/tick-sched.c
@@ -20,6 +20,7 @@
#include <linux/profile.h>
#include <linux/sched.h>
#include <linux/tick.h>
+#include <asm/irq_regs.h>
#include "tick-internal.h"
Index: linux-2.6.20-rc6/arch/arm/kernel/process.c
===================================================================
--- linux-2.6.20-rc6.orig/arch/arm/kernel/process.c
+++ linux-2.6.20-rc6/arch/arm/kernel/process.c
@@ -28,6 +28,7 @@
#include <linux/cpu.h>
#include <linux/elfcore.h>
#include <linux/pm.h>
+#include <linux/tick.h>
#include <asm/leds.h>
#include <asm/processor.h>
@@ -154,11 +155,11 @@ void cpu_idle(void)
if (!idle)
idle = default_idle;
leds_event(led_idle_start);
- hrtimer_stop_sched_tick();
+ tick_nohz_stop_sched_tick();
while (!need_resched() && !need_resched_delayed())
idle();
leds_event(led_idle_end);
- hrtimer_restart_sched_tick();
+ tick_nohz_restart_sched_tick();
local_irq_disable();
__preempt_enable_no_resched();
__schedule();
================================================================================
================================================================================
Updated version of i.MX patch follows. If somebody wants it,
I can send patch to revert code of previous version from
full 2.6.20-rc6-rt2 patch.
Ingo, please, can you replace i.MX1 patch in your series?
Thanks
Pavel
================================================================================
================================================================================
Subject: arm: i.MX/MX1 clock event source
Support clock event source based on i.MX general purpose
timer in free running timer mode.
Signed-off-by: Pavel Pisa <pisa@....felk.cvut.cz>
arch/arm/mach-imx/time.c | 130 +++++++++++++++++++++++++++++++++++++++++++++--
1 file changed, 125 insertions(+), 5 deletions(-)
Index: linux-2.6.20-rc6/arch/arm/mach-imx/time.c
===================================================================
--- linux-2.6.20-rc6.orig/arch/arm/mach-imx/time.c
+++ linux-2.6.20-rc6/arch/arm/mach-imx/time.c
@@ -15,6 +15,9 @@
#include <linux/irq.h>
#include <linux/time.h>
#include <linux/clocksource.h>
+#ifdef CONFIG_GENERIC_CLOCKEVENTS
+#include <linux/clockchips.h>
+#endif
#include <asm/hardware.h>
#include <asm/io.h>
@@ -25,6 +28,11 @@
/* Use timer 1 as system timer */
#define TIMER_BASE IMX_TIM1_BASE
+#ifdef CONFIG_GENERIC_CLOCKEVENTS
+static struct clock_event_device clockevent_imx;
+static enum clock_event_mode clockevent_mode = CLOCK_EVT_MODE_PERIODIC;
+#endif
+
static unsigned long evt_diff;
/*
@@ -33,6 +41,7 @@ static unsigned long evt_diff;
static irqreturn_t
imx_timer_interrupt(int irq, void *dev_id)
{
+ unsigned long tcmp;
uint32_t tstat;
/* clear the interrupt */
@@ -42,13 +51,20 @@ imx_timer_interrupt(int irq, void *dev_i
if (tstat & TSTAT_COMP) {
do {
+#ifdef CONFIG_GENERIC_CLOCKEVENTS
+ if (clockevent_imx.event_handler)
+ clockevent_imx.event_handler(&clockevent_imx);
+ if (likely(clockevent_mode != CLOCK_EVT_MODE_PERIODIC))
+ break;
+#else
write_seqlock(&xtime_lock);
timer_tick();
write_sequnlock(&xtime_lock);
- IMX_TCMP(TIMER_BASE) += evt_diff;
+#endif
+ tcmp = IMX_TCMP(TIMER_BASE) + evt_diff;
+ IMX_TCMP(TIMER_BASE) = tcmp;
- } while (unlikely((int32_t)(IMX_TCMP(TIMER_BASE)
- - IMX_TCN(TIMER_BASE)) < 0));
+ } while (unlikely((int32_t)(tcmp - IMX_TCN(TIMER_BASE)) < 0));
}
return IRQ_HANDLED;
@@ -70,7 +86,7 @@ static void __init imx_timer_hardware_in
*/
IMX_TCTL(TIMER_BASE) = 0;
IMX_TPRER(TIMER_BASE) = 0;
- IMX_TCMP(TIMER_BASE) = LATCH - 1;
+ IMX_TCMP(TIMER_BASE) = IMX_TCN(TIMER_BASE) + LATCH;
IMX_TCTL(TIMER_BASE) = TCTL_FRR | TCTL_CLK_PCLK1 | TCTL_IRQEN | TCTL_TEN;
evt_diff = LATCH;
@@ -87,7 +103,7 @@ static struct clocksource clocksource_im
.read = imx_get_cycles,
.mask = 0xFFFFFFFF,
.shift = 20,
- .is_continuous = 1,
+ .flags = CLOCK_SOURCE_IS_CONTINUOUS,
};
static int __init imx_clocksource_init(void)
@@ -99,11 +115,115 @@ static int __init imx_clocksource_init(v
return 0;
}
+#ifdef CONFIG_GENERIC_CLOCKEVENTS
+
+static int imx_set_next_event(unsigned long evt,
+ struct clock_event_device *unused)
+{
+ unsigned long tcmp;
+ evt_diff = evt;
+
+ tcmp = IMX_TCN(TIMER_BASE) + evt;
+ IMX_TCMP(TIMER_BASE) = tcmp;
+
+ return unlikely((int32_t)(tcmp - IMX_TCN(TIMER_BASE)) < 0) ? -ETIME : 0;
+}
+
+#ifdef DEBUG
+static const char *clock_event_mode_label[]={
+ [CLOCK_EVT_MODE_PERIODIC] = "CLOCK_EVT_MODE_PERIODIC",
+ [CLOCK_EVT_MODE_ONESHOT] = "CLOCK_EVT_MODE_ONESHOT",
+ [CLOCK_EVT_MODE_SHUTDOWN] = "CLOCK_EVT_MODE_SHUTDOWN",
+ [CLOCK_EVT_MODE_UNUSED] = "CLOCK_EVT_MODE_UNUSED"
+};
+#endif /*DEBUG*/
+
+static void imx_set_mode(enum clock_event_mode mode, struct clock_event_device *evt)
+{
+ unsigned long flags;
+
+ /*
+ * The timer interrupt generation is disabled at least
+ * for enough time to call imx_set_next_event()
+ */
+ local_irq_save(flags);
+ /* Disable interrupt in GPT module */
+ IMX_TCTL(TIMER_BASE) &= ~TCTL_IRQEN;
+ if ((mode != CLOCK_EVT_MODE_PERIODIC) || (mode != clockevent_mode)) {
+ /* Set event time into far-far future */
+ IMX_TCMP(TIMER_BASE) = IMX_TCN(TIMER_BASE) - 3;
+ /* Clear pending interrupt */
+ IMX_TSTAT(TIMER_BASE) &= ~TSTAT_COMP;
+ }
+
+#ifdef DEBUG
+ printk(KERN_INFO "imx_set_mode: changing mode from %s to %s\n",
+ clock_event_mode_label[clockevent_mode], clock_event_mode_label[mode]);
+#endif /*DEBUG*/
+
+ /* Remember timer mode */
+ clockevent_mode = mode;
+ local_irq_restore(flags);
+
+ switch (mode) {
+ case CLOCK_EVT_MODE_PERIODIC:
+ /* It seems, that periodic mode expects old ugly latch period */
+ evt_diff = LATCH;
+ IMX_TCMP(TIMER_BASE) = IMX_TCN(TIMER_BASE) + evt_diff;
+ case CLOCK_EVT_MODE_ONESHOT:
+ /*
+ * Do not put overhead of interrupt enable/disable into
+ * imx_set_next_event(), the core has about 4 minutes
+ * to call imx_set_next_event() or shutdown clock after
+ * mode switching
+ */
+ local_irq_save(flags);
+ IMX_TCTL(TIMER_BASE) |= TCTL_IRQEN;
+ local_irq_restore(flags);
+ break;
+ case CLOCK_EVT_MODE_SHUTDOWN:
+ case CLOCK_EVT_MODE_UNUSED:
+ /* Left event sources disabled, no more interrupts appears */
+ break;
+ }
+}
+
+static struct clock_event_device clockevent_imx = {
+ .name = "imx_timer1",
+ .features = CLOCK_EVT_FEAT_PERIODIC | CLOCK_EVT_FEAT_ONESHOT,
+ .shift = 32,
+ .set_mode = imx_set_mode,
+ .set_next_event = imx_set_next_event,
+ .rating = 200,
+};
+
+static int __init imx_clockevent_init(void)
+{
+ clockevent_imx.mult = div_sc(imx_get_perclk1(), NSEC_PER_SEC,
+ clockevent_imx.shift);
+ clockevent_imx.max_delta_ns =
+ clockevent_delta2ns(0xfffffffe, &clockevent_imx);
+ clockevent_imx.min_delta_ns =
+ clockevent_delta2ns(0xf, &clockevent_imx);
+
+ clockevent_imx.cpumask = cpumask_of_cpu(0);
+
+ clockevents_register_device(&clockevent_imx);
+
+ return 0;
+}
+#endif
+
+
static void __init imx_timer_init(void)
{
imx_timer_hardware_init();
imx_clocksource_init();
+#ifdef CONFIG_GENERIC_CLOCKEVENTS
+ imx_clockevent_init();
+#endif
+
/*
* Make irqs happen for the system timer
*/
-
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